Drawing boards with counterbalancing mechanism



Feb. 26, 1963 B. MORCHELES 3,078,613

DRAWING BOARDS WITH COUNTER-BALANCING MECHANISM Filed April 11, 1962 25 FIG/5 INVENTOR, BERNARD MORCHELES,

BY W ATTORNEY 3,078,613 DRAWING BOARDS WITH COUNTER- BALANC G MECHANISM Bernard Morcbeles, South Orange, N.J., assignor to Stacor Corporation, Newark, N.J., a corporation of New Jerse y Filed Apr. 11, 1962, Ser. No. 186,719

12. t'ilaims. (Cl. 45--131) The present invention relates to drafting desks and the like in which the drawing board is tiltably adjustable and more particularly to counter-balancing mechanism for the board while it is released to be swung to any desired position.

An object of this invention is to provide a novel and improved counter-balancing means to compensate for the weight of the drawing board so that its tilt may be changed with a minimum of effort and particularly when the board is near vertical position, it shall not over-balance and fall towards the draftsman.

- Another object thereof is to provide a novel and improved counter-balancing means of the character mentioned, affording adjustment to account for the Weight of any accessories, as for instance a drafting machine that may be attached to the board.

a A further object of this invention is to provide a novel and improved counter-balancing means of the kind described, having the mentioned attributes and which is simplein construction, easy to adjust, reasonable in cost and efiicient in carrying out the purposes for which it is designed. i I i Other objects and advantages will becomeapparent as this disclosure proceeds.

For the practice of this invention, one form it may assume is-to have the drawing board with downwardly extending brackets, one at each forward corner. Near bottom end, each bracket is pivoted to a vertical, side post of the drafting desk or table frame; said posts being between the brackets. The pivotal connections have a common axis line, so the board is swingably mounted to allow change of 'its tilt. The board is associated with some suitable clutch means for example, adapted to releasably hold it in any set position and upon pressing down on a pedal or by a manipulation of some other form of control, the board is released for swinging.

As mentioned, this invention concerns itself with means to afford counter-balancing action while the board is free to be swung. I prefer to have one such means carried on each bracket and part on the related post.

Each counter-balancing mechanism comprises a bellcrank which is free to turn on the axis pin of the boards pivotal connection. One arm of said bell-crank extends rearwardly where means on the post determines the limits of its movement or holds it against movement; all this, being adjustable. The other arm of said bell-crank extends upwardly forwardly and is within the confines of the bracket. There are two members arranged in slidable relation to form an extensible and contractable unit. One end of this unit is swingably mounted near the upper end of the bracket and its other end is pivotally linked to the forwardly extending arm of the bell-crank. Spring means on said unit, biases it to contract and the spring stress is adjustable.

I will now give a detailed description of the particular embodiment illustrated and its mode of operation.

In the accompanying drawing forming part of this specification, similar characters of reference indicate corresponding parts in all the views.

FIG. 1 is a perspective view of a drafting desk embody-' ing the teachings of this invention. Part is in section.

FIG. 2 is 'an enlarged front view of the counter-balancing means which is at the right of the desk in FIG. 1.

3,078,613 Patented Feb. 26, 1963 ice There is a similar means at the left side. Both such means are identical, except that one is right and the other left. In FIG. 1, said means are shown enclosed. In FIG. 2, the outer casing is omitted so the counter-balancing mechanism is exposed.

FIG. 3 is section taken at line 33 in FIG. 2, drawn to an enlarged scale. The mechanism is shown in full lines where the drawing board position is horizontal and in broken lines Where the board is in a tilted position.

FIGS. 4-6, drawn to the scale of FIG. 2, are rear views of part of FIG. 2, shown dilferently set for adjustments which will be explained.

In the drawing, the numeral 15 designates generally a drafting desk whose separate drawing board 16 at each front corner, has a downwardly extending bracket as 17 which is pivotally mounted near its bottom end on the stud pin 18 extending from the desk frame post 19. Suitable mechanism well known in the art, but not shown because it is no part of this invention, includes some sort of clamping or clutch means to hold the board 16 releasably fixed in any set position, and for instance, by pressing down on a pedal 20, to release the board for swinging movement. The axis of swing of the board is provided by said pin 18 and its mate at the other side of the board; said pins being in alignment.

Since the counter-balancing means 21, 21' are of identical construction, except that one is right and the other left, a description of one and everything else said about it herein, will sufiice for the other.

On the axis pin 18, there is the turnable bell-crank 22, having its arm 23 extending rearwardly through a vertically elongated opening 24 in a plate 25 which is fixed on the rear surface of the post 19. The other arm 26 of said bell-crank, extends forwardly upwardly. There is an extensible contractable unit denoted generally by the numeral 27 which extends along the bracket 17. It is made of two members 28 and 29 which are in slidable relation and spring-biased by 30 to contract. One end of this unit is swingably mounted on a pin 31 fixed to the bracket near its upper end, and the other end of said unit is pivotally linked by a pin 32 to the bell-crank arm 26.

In the particular construction illustrated, the member 29 is an eye-bolt which is through the hole 33 in a bridge piece 34 spanning and integral with the distal ends of an inverted U-piece 35, constituting the member 28. The compression coil spring 30 which is of chosen strength to do its required work, is on the member 29, between the legs of the U-pliece 35 and resting on the bridge piece 34. At the end of the eye-bolt is the nut 36 resting against the washer 37 which in turn is against the end of said spring 30. It is evident that the initial stress in said spring can be regulated by turning said nut 36.

' On the plate 25 :is a plate arm 38, swingably mounted on an axis 39. This plate arm has a notch denoted generally by the numeral 40 which decreases in width so that in one position as shown in FIG. 4, the bell-crank arm 23 which may be a circular pin which is to be noted,

passes through such notch, is held against movement,

that is, the bell-crank 22 is held from turning. When said plate arm 38 is in the position shown in FIG. 5, the bell-crank is allowed a predetermined amount of turning movement and when said plate arm is in the position shown in FIG. 6, the bell-crank is allowed a greater amount of turn as determined by the slot 24 in the plate 25. In essence, the plate arm in its positions of FIGS. 4 and 5, closes portions of the slot 24, a different total amount at each such position. Said plate arm 38 has a finger piece 41 for its manipulation; the similar finger piece for the counter-balancing means 21', being shown at 4-1. To hold the plate arm at its various positions,

it may carry a spring-biased ball detent 42 for releasable co-operationin the respective holes 43, 44, 45 in the fixed plate 25. W 1 H I i We willassume that the plate arm 38-is in the position shown in FIG. 4, where they bell-crank 22 is held stationary. We will now note that the locus of movement 5 of the pin 311s along the circumference or the'circle' C whose radius is R and whose center isthat of the axis offered by the pin 18, whilethelocus 'of movement 1 oiithefreeend' of the eye-bolt 29 is along the circum ference 0t thecircleJCf whose radius is'fR and whose center'isthat bf the axis offered 59 the pivotal connected at 32.; It" nurse tiote'd that as the bond "16 is'swu'ng from hQriZontal position, said 16bit approach ehch 'o'thfi This tenses the spring 30 to lengthen 'aii'd consequently the stress therein decreases. "This occurs up to a certain point and astheboard is then shifted further to approach vertic ahsaid loci digress. This causes the s'pringStIt" shorteri and its stress is thereby inbreased," The: position of the axis 32jis s o chosen'tha't the minimum stress occurs the spring 30 whe n'the' draw n board is at aboutja" 20 fifty degree angle frorii'horizontal'fwhich isthe position at which'the board is normally balance. At thisipoiiit," there may be no "stress 'in' the spring. It becomes, evident" e e In e ti f' l n s mi m ni ges iib heb ardj fifl sflfi m nq'a n w e ts is? Ihfieks m an qwn n 16. is wa e e, it a cban ct pnlpf h m mb r 9 m y, b tl i' z. able point on th L fiqred post 19:, where the mentioned loci will have the relationship described.

he m chanis n 4s 2t9rY-i adr diustms f the nut 36 when thel bell-crank 22 is heldfixed,by havingiits rmfin 'oxii lete wins as n IG- 41 F 2 e amountof initial compression'of the spring 30, to account l fonthe weight of the board 16, and also a consumermadeadjuslt ne nt of, th plate arni 33 to account, for the. weight ofjtheaccesspries, as "for instance" a lamp 'or draft-i mg fiiag inei e fio il wh c have b eni'a tac edl him to the board, 'Thi latter' adiu i tent "allows'fthe beltmb m, varyin ,degiee' "otrre more f "1 rhinedby jefposiltionofflthe'pia mea ssnewnin 40 the nos; 5 was." "It is evident. tliaitfsihce. there similar selector me n including the plateiarliii manipul '1 b 41j as there isl which, isiii anipulatedlby movement n: the finger-piece .41, many, ran s'ffof .counter-balancei'canj be attained. by combinationsof. any. "one of the three; conditionsat 21 with 'anyorie'ot the conditions n21; meaningthe conditions respectively. shown in the FIGS.

The term counter-balancing action as herein employed, is. the resistance offered by'thefcounter balancin'g meansZl, 21, tothe drawingboard. in its movement. Wheri'the drawing boar'd ,16, has no appurtenances, restraining action to its' movement need only take place to avoid its falling down to horizontal and tofavoid its .fiip pingifor' w'ard tohit the draftsin'an'when the pedal 20 is'pr'esseddownwa'rd to 'rele'ase the clutch. In such in stanc e the board may have ,a free movement for. a. determined angle. inter mediate; horizontal and vertical and a less restrained movement elsewhere than would be re-' if the, board carriedfa load. Such is offered by ne ating shown'inFIG. 6, where the bellcranks arm 23 is a tI ordeda measured free movement determined by the ends of the slot 24. a

Ininstances wh re the board 1 6, carries what may be deemed a lrnoderate load, control of board movement 511511111 occufduring greater end portions of its swing. Hence, there will b'e a lesser angle where its free move: meat is' to be permitted; This "is afforded by the'settin'g shown in FIG. 5 where the bell-cranks arm 23 is allowed" arnea'su red, comparatively smaller 'free swing movement as determined by the opposite notch edges 47, 47, they distance between such notch edges being less than the distance between the ends oftthe slot 24.

In installations wheretheboard 16 is, heavily, laden, uomovernent "should be allowed the saidboard, which isnmestrained. For such, we use thesettingshown in FIG. 4, where the bell-cranks arin 23 is held stationary in the notch48iin which said arm fits.

Adjustment of both counter-balancing means 21, 21' are made identical, but if desired where both means are employed, their settings may be made different, to change the maximumrestraint tolb'e otfered board movement, as load conditions or, the desireof the user, may dictate.

The manufacturerfwilLchoosethe length of ,the slotm 24 t andthelesseridista e betweenthe'jnotch edges Q41, 47', to accomplish the fespectiii e'xte'ritsof'freeswing movement desired, that is,fto lac t,as suitabl e stops."

This inventionislcapable oi numerousl'forms and various applications without departing from the essential features herein "set forth It 'is therefore intended and desired; I that? the? embodiment shown herein. shall be? deemed mer'ely"'illustrative and not restrictive and that the patent'shall cover all patentable n'ovel'ty' herein dis-' closed referencebeing had to the following claims rather than tothespecific'; description herein toindicate the scope of this invention.

I'claim:

1; In' a counterbalanced. drawing board construction of the character described, a frame, a drawing board, and; a counter-balancingunit comprising abracket extending" downwardly from said -board;-:'said bracket; near its hottomerid,'"be ing swingably mounted on the frame for moyement about a horizontal axis which is nearer to the front edge of said board than to the rear edge thereof,. an extensible and contractable "str'ucture including, a spring Bias'ing'said structure to contract, a first 'pin"carri'ed on"said'frarrijin'tront offrelati'vely near and in fixed relation to' said aids, and a'se'cond pin'ca'rried by said'fbraclget'ahove said a'xi's; tlie"en"ds of said extensible and 'cemrsetable structure" being" pivotally linked to said pins respectively; the respective locations of said pins be ing "s'uch'that the'stfe's s intli''pi'ing isneerea'sedas'th board is swung from a horizontal position to 'one"where said board isat a"predete' "rrnin'edslope,"and increased wnenjthesto e fdf said board is greater than such pre det'iefinined'slope."

2." AEoun r b'alanced d rawing board construction as defined'iii cairn '1; including means onsaid eite'n'siblef andicoiitractable"structure, for adjusting thestfess in'said 3'. A counter-balanced drawing board construction as defined reclaim" 1'1" inclu'ding a mem er "swingably' mounted on the frame forniovemerit about a horizontal aids; the firstpin being carried on said member, and a stop means" on the frame allowing'said'mei'nhler a pre deti'rriinedscope of, swirig'ing' movemen A counterbalanced drawiiig board construction as defined in claim L inclliding a rnember SiYiIigably mounted on the frame, for inovmeht about a horiziontal atxis; the first, pin ,being'lcarried' on said member, and stop means "movahlyjmounted 'on'the frame; said s t op means t Pa t b din 'aa .me j e i nd t another position, allowing 'sfaid' member a predetermined scopeiof swinging movement.

51 A "coiinter-balanced drawing, board construction as defined I in clai r n:' 1, including faj bell-craHIcGwingablyQ mounted. on the frame for movement 'a bouta" horizontal axisjthe first pin being carriedlon one 'arm ofsaid bell ciank an d a stop means on the frarneallowirig said bell r nk a 'i sts 's ops g sw n ins o e e he othe'rjarrri of said 'bell crank, contacting said stop means at the limitsof travel of said h'ell 'crank,

6. A, counterrhalanced drawing board construction as defined l in claim fl, incl ldi gj" a bell-crank," swingably mounted on theiframe foi'frii'ovenient aboutf a horizontal' axis; the fit'jsftpir't h ng carried on one arr'ni of, said b'ellq crank aiid's't'op' mean's'mbvablyfnjtojinted on "thefrante; s's idstop, means at, one PQ'SiFn, holding the otherarm' ofthebell igrank; stationary d atjan'othierj position, alow a id bellerankgaj'plredefc. mined pe of w in movement in which instance the other arm of said bellcrank contacts said stop means at the limits of travel of said bell-crank, respectively.

7. A counter-balanced drawing board construction as defined in claim 1, including a second similarly composed counter-balancing unit, similarly associated with the drawing board; the axes of swing of the brackets of said units, being colinear; each of said units including a member swiugably mounted on the frame for movement about a horizontal axis; the first pin of each said unit being carried on said members respectively, and stop means for each of said units, movably mounted on the frame; each said stop means at one position, respectively holding said member which is associated therewith, stationary, and at another position respectively, each of said members are allowed a predetermined scope of movement respectively.

8. A counterbalanced drawing board construction as defined in claim 7, wherein each of said stop means is independently movable.

9. A counter-balanced drawing board construction as defined in claim 7, including means on each of the extensible, contractable structures of said units, for independently adjusting the stress in the respective springs.

10. A counter-balanced drawing board construction as defined in claim 1, including a second similarly composed counter-balancing unit, similarly associated with the drawing board; the axes of swing of the brackets of said units, being colinear; each of said units including a bell-crank swingably mounted on the frame for movement about a horizontal axis; the first pin of each said units being carried on one arm of said bell-cranks respectively, and stop means for each of said units, movably mounted on the frame; each said stop means at one position respectively, holding the other arms of said bell-cranks respectively, stationary, and at another position respectively, allowing said bell-cranks a predetermined scope of swinging movement respectively, in which instances at said second positions respectively, said other arms of said bellcranks respectively, contact the stop means related therewith, at the limits of travel of said bell-cranks respectively.

11. A counter-balanced drawing board construction as defined in claim 10, wherein each of said stop means is independently movable.

12. A counter-balanced drawing board construction as defined in claim 10, including means on each of the extensible, contractable structures of said units, for independently adjusting the stress in the respective springs.

References Cited in the file of this patent UNITED STATES PATENTS 2,833,081 Pottern May 6, 1958 2,998,672 Sautereau Sept. 5, 1961 3,012,363 Sautereau Dec. 12, 1961 3,043,048 Bergman July 10, 1962 3,052,057 May et al. Sept. 4, 1962 

1. IN A COUNTER-BALANCED DRAWING BOARD CONSTRUCTION OF THE CHARACTER DESCRIBED, A FRAME, A DRAWING BOARD, AND A COUNTER-BALANCING UNIT COMPRISING A BRACKET EXTENDING DOWNWARDLY FROM SAID BOARD; SAID BRACKET, NEAR ITS BOTTOM END, BEING SWINGABLY MOUNTED ON THE FRAME FOR MOVEMENT ABOUT A HORIZONTAL AXIS WHICH IS NEARER TO THE FRONT EDGE OF SAID BOARD THAN TO THE REAR EDGE THEREOF, AN EXTENSIBLE AND CONTRACTABLE STRUCTURE INCLUDING A SPRING BIASING SAID STRUCTURE TO CONTRACT, A FIRST PIN CARRIED ON SAID FRAME, IN FRONT OF, RELATIVELY NEAR AND IN FIXED RELATION TO SAID AXIS, AND A SECOND PIN CARRIED BY SAID BRACKET ABOVE SAID AXIS; THE ENDS OF SAID EXTENSIBLE AND CONTRACTABLE STRUCTURE BEING PIVOTALLY LINKED TO SAID PINS RESPECTIVELY; THE RESPECTIVE LOCATIONS OF SAID PINS BEING SUCH THAT THE STRESS IN THE SPRING IS DECREASED AS THE BOARD IS SWUNG FROM A HORIZONTAL POSITION TO ONE WHERE THE SAID BOARD IS AT A PREDETERMINED SLOPE, AND INCREASED WHEN THE SLOPE OF SAID BOARD IS GREATER THAN SUCH PREDETERMINED SLOPE. 